Update bank_support.py example (#868)

Author: kauabh

examples/pydantic_ai_examples/bank_support.py

@@ -26,7 +26,7 @@ async def customer_name(cls, *, id: int) -> str | None:
 
     @classmethod
     async def customer_balance(cls, *, id: int, include_pending: bool) -> float:
-        if id == 123:
+        if id == 123 and include_pending:
             return 123.45
         else:
             raise ValueError('Customer not found')